In order to meet the demands required by today's lubricating oils, in particular, crankcase lubricating oils, there is a continuing effort to find new and improved lubricant additives. Such additives include antioxidants which permit the lubricating oil to withstand high temperatures without excessive breakdown of the oil and friction modifiers which reduce the friction between lubrication surfaces. Friction modifiers when used in the crankcase of an internal combustion engine reduce the engine's fuel consumption.
Copper oleate has been described in British Pat. No. 2,056,482 as an effective antioxidant. While copper oleate is an effective antioxidant in crankcase lubricants, the prior art failed to recognize that copper oleates cause degradation of the rust and copper/lead bearing corrosion performance of such lubricants. It has now been found that the copper salt compositions of the instant application are effective antioxidants for crankcase lubricants without the deleterious effect on rust and copper/lead bearing corrosion performance that accompanies copper oleate. Furthermore, the copper salt compositions of the instant application are effective friction modifiers.